Javac 与 Java CommandLine Operations

Javac

 

javac [ options ] [ sourcefiles ] [ classes ] [ @argfiles ]

Arguments may be in any order.

options

Command-line options.

sourcefiles

One or more source files to be compiled (such as MyClass.java).

classes

One or more classes to be processed for annotations (such as MyPackage.MyClass).

@argfiles

One or more files that lists options and source files. The -J options are not allowed in these files.

There are two ways to pass source code file names to javac:

• For a small number of source files, simply list the file names on the command line.
• For a large number of source files, list the file names in a file, separated by blanks or line breaks. Then use the list file name on the javac command line, preceded by an @ character.

Inner class definitions produce additional class files. These class files have names combining the inner and outer class names, such as MyClass$MyInnerClass.class.

You should arrange source files in a directory tree that reflects their package tree.The source code for com.mysoft.mypack.MyClass should be in C:\workspace\com\mysoft\mypack\MyClass.java.

You can specify a separate destination directory with -d.

-d directory

Set the destination directory for class files. The directory must already exist; javac will not create it. If a class is part of a package, javac puts the class file in a subdirectory reflecting the package name, creating directories as needed. For example, if you specify -d C:\myclasses and the class is called com.mypackage.MyClass, then the class file is called C:\myclasses\com\mypackage\MyClass.class.

If -d is not specified, javac puts each class files in the same directory as the source file from which it was generated.

Note: The directory specified by -d is not automatically added to your user class path.

Non-standard options begin with -X.

-cp path or -classpath path

Specify where to find user class files, and (optionally) annotation processors and source files. This class path overrides the user class path in the CLASSPATH environment variable. If neither CLASSPATH, -cp nor -classpath is specified, the user class path consists of the current directory.

If the -sourcepath option is not specified, the user class path is also searched for source files.

If the -processorpath option is not specified, the class path is also searched for annotation processors.

Setting the class path

The class path is the path that the Java runtime environment searches for classes and other resource files. 

classpath1;classpath2

Class paths to the .jar, .zip or .class files. Each classpath should end with a filename or directory depending on what you are setting the class path to:

• For a .jar or .zip file that contains .class files, the class path ends with the name of the .zip or .jar file.
• For .class files in an unnamed package, the class path ends with the directory that contains the .class files.
• For .class files in a named package, the class path ends with the directory that contains the "root" package (the first package in the full package name).

Multiple path entries are separated by semi-colons. With the set command, it's important to omit spaces from around the equals sign (=).

The default class path is the current directory. Setting the CLASSPATH variable or using the-classpath command-line option overrides that default, so if you want to include the current directory in the search path, you must include "." in the new settings.

Classpath entries that are neither directories nor archives (.zip or .jar files) nor * are ignored.

 

-g

Generate all debugging information, including local variables. By default, only line number and source file information is generated.

-g:none

Do not generate any debugging information.

-g:{keyword list}

Generate only some kinds of debugging information, specified by a comma separated list of keywords. Valid keywords are:

 

source

Source file debugging information

lines

Line number debugging information

vars

Local variable debugging information

-Joption

Pass option to the java launcher called by javac. For example, -J-Xms48m sets the startup memory to 48 megabytes. It is a common convention for -J to pass options to the underlying VM executing applications written in Java.

Note: CLASSPATH, -classpath, -bootclasspath, and -extdirs do not specify the classes used to run javac. Fiddling with the implementation of the compiler in this way is usually pointless and always risky. If you do need to do this, use the -J option to pass through options to the underlying java launcher.

-sourcepath sourcepath

Specify the source code path to search for class or interface definitions. As with the user class path, source path entries are separated by semicolons (;) and can be directories, JAR archives, or ZIP archives. If packages are used, the local path name within the directory or archive must reflect the package name.

Note: Classes found through the class path may be subject to automatic recompilation if their sources are also found.

 

 

Java

java [options] classname [args]

options

Command-line options separated by spaces. See Options.

classname

The name of the class to be launched.

filename

The name of the Java Archive (JAR) file to be called. Used only with the -jar option.

args

The arguments passed to the main() method separated by spaces.